On Thu, Jun 18, 2020 at 02:17:15PM -0700, syzbot wrote: > INFO: trying to register non-static key. > the code is fine but needs lockdep annotation. > turning off the locking correctness validator. > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xf6/0x16e lib/dump_stack.c:118 > assign_lock_key kernel/locking/lockdep.c:894 [inline] > register_lock_class+0x1442/0x17e0 kernel/locking/lockdep.c:1206 > arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25 > lock_downgrade+0x720/0x720 kernel/locking/lockdep.c:4624 > is_dynamic_key+0x1b0/0x1b0 kernel/locking/lockdep.c:1176 > trace_hardirqs_off+0x50/0x1f0 kernel/trace/trace_preemptirq.c:83 > __lock_acquire+0x101/0x6270 kernel/locking/lockdep.c:4259 > save_stack+0x32/0x40 mm/kasan/common.c:50 So I'm thinking this is in fact: spin_lock_irqsave(&depot_lock, flags); from lib/stackdepot.c:stack_depot_save(), which has gone missing from the stack due to tail-call optimizations. Now depot_lock is declared thusly: static DEFINE_SPINLOCK(depot_lock); and I'm trying to figure out how lockdep manages to conclude that isn't static storage.... most odd.
